Patent GB-841460-A (GB)
Title: Improvements in or relating to systems for detecting particular pulse combinations
IPC: H04L17/16
Filed: 1958-09-17
Abstract: 841,460. Code telegraphy. SIEMENS & HALSKE A.G. Sept. 17, 1958 [Sept. 17, 1957], No. 29775/58. Class 40(3). An arrangement for detecting a predetermined binary code combination in a train of code combinations includes a differential relay to one or the other winding of which the successive pulses of each combination are passed by a distributer and operates in such a manner that when the particular code combination is received the differential relay is held in one of its operated positions for the full duration of a code combination, whilst in response to any other code combination the relay is in its other position at the end of that coded impulse combination. The received impulses operate a relay member e between a marking contact T and a spacing contact Z, and contacts ak1-ak5 are closed in succession by the distributer. Contacts bl-b5 associated with the contacts ak1-ak5 are connected selectively to contacts z1-z5 or tl-t5 in accordance with the code combination of the predetermined signal. The two sets of contacts z1-z5 and tl-t5 are connected in parallel respectively to the windings I, II of the relay S. At the beginning of a code combination the contact s of relay S is against its contact T and a contact an1 moved to the position opposite that shown at the beginning of a code combination is held in that position during the sequence of the signals. The windings I, II of relay S are such that the currents derived from a z contact or a t contact hold the relay with its member s against the contact T so that if the received signal impulses correspond to the z or t connections of the terminals b, the relay S is permanently held in the position shown, and the operation of contacts nk1 to the position opposite that shown at the end of a code combination operates relay AZ which at contact az1 lights a lamp L indicating that the particular signal has been received. If the received signal differs from the predetermined code combination, the positioning of the armature e in response to an impulse will be at variance with the selective connection from a b terminal and the current through the winding I or II will be reversed in relation to its direction to hold the member s against the contact T, and it now moves against contact Z so that a circuit is closed for winding III of relay S which is such as to hold the member s against contact Z even if any subsequent impulse of the combination is such that it corresponds with the selective connection of its b terminal and the current from its z or t terminal thereby tending to restore the relay S to the condition with its contact s against the contact T. At the end of the code combination when the contacts nkl, nk2 assume the positions opposite to those shown, relay AZ is not operated and the lamp L is not illuminated. Also the circuit of winding III of relay S is opened at contact nkl the capacitor Cn is charged positively and when the contact nk2 is restored to the position shown the winding III of relay S is energized in the direction to restore the member s to the position shown against contact T.